There has heretofore been known, as described for example in U.S. Pat. No. 3,262,872, the use for a torch or the like of a mixture of hydrogen and oxygen gases generated by electrolytic decomposition of water and ignited to produce a flame for welding, brazing or the like. This technique typically employs a pair of electrodes immersed in electrolytically conductive water and juxtaposed with one another in a tightly closed tank containing the water, the electrodes being energized by a direct-current power supply for passing an electric current therebetween to electrolytically generate hydrogen and oxygen gases. The hydrogen and oxygen gases may be evolved into a space above the surface of the water in the tank to form a mixture thereof which is led through a conduit to a torch or nozzle where it is to be ignited. In order to ensure a stabilized production of the flame from the electrolytically generated gases, it is required or desirable to generate the gases at a sufficient rate and with efficiency, to deliver the gases at a constant amount and under a constant pressure and further to assure that the gases delivered be free from steam, moisture or aqueous condensate (i.e., to be sufficiently dry). To this end, various measures have been proposed including the use of a plurality of electrically conductive cylinders as electrodes concentrically arranged in the water tank for energization by the power supply to produce gases at plural locations as well as the floating of a hydrocarbon in an attempt to control the aqueous evaporation, all with only limited success.